• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1176-1185
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• 1993

The purpose of this study is to propose a new dynamic model of wheels and agricultural tractors through verification of the existence of " lift resistance " and "perpendicular adhesion" which also can be called " contra-retractive adhesion". The existence of these forces was proved through experiments including the development of a sensor which can measure the forces acting on a wheel accurately. Consequently " perpendicular adhesion ratio" which is defined as the ratio of the perpendicular adhesion to the distributed load was observed to be in the range of 0.05 to 0.3. This means the influence of the " lift resistance " is comparable to that of motion resistance in wheel dynamics. The perpendicular adhesion ratio was observed to decrease logarithmically with the increase of ground contact pressure, and to increase linearly with increase of the travel speed of the wheel . Some examples to express the new dynamic model compared to the conventional dynamics are explained.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.379-384
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• 2014

This article describes the dynamic behaviors of a rubber tired gantry crane(RTGC) under typical load conditions which are used in the design of gantry cranes. In order to investigate the dynamic characteristics of an RTGC, we developed a finite element crane model for its huge structure. The finite element model was validated with the modal test results, e.g., natural frequencies and normal modes. And other components of RTGC were converted into detailed 3D CAD models and finally transformed to rigid body models in a dynamic simulation program ADAMS. The load conditions considered in this paper were a normal operating condition(OP1) and container hanging condition with no external loads. As a result, we could find there was large influence of crane's vibration owing to its structural stiffness and deformation. And the vibration of crane could made the movements of RTGC, which occurs crash or malfunction of crane works.

• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.678-686
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• 2009

A trial run of locally-developed tilting train has been in process on Chungbuk line since the test vehicle was first produced. For the system stabilization, interface verification among the systems including track, structure, catenary and signaling system, not to mention the rolling stock, is very crucial. Therefore, in this study, the dynamic rail force of the tilting (Hanvit 200), high-speed (KTX) and general (Mugunghwa) vehicle caused by driving in transition curve track was measured. And, it compared the tilting response with the other by using the measured rail force data in transition curve track, and then evaluated probability the range of load fluctuation for the variable dynamic vertical and lateral wheel load. As a result, a range of rail force by occurred a change of cant from the high-speed and general vehicle which had fixed bogie structure was distributed throughout small deviation. Otherwise, in case of the tilting train which was consisted of the pendulum bogie structure was distributed wide range about large deviation by changed of cant.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.863-869
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• 2002

Studied in this paper was the kinematic envelope of the railway vehicle to calculate the lateral displacement using the multi-body dynamic simulation program (VAMPIRE) and the BASS 501. The lateral displacement of railway vehicle is occurred by the clearance between wheel flange and rail, the track irregularity, the property of each suspension of vehicle and the cant of track etc. The results of analysis shown that Vehicle is not interfere with subway platform in any conditions namely the tare and full load condition, the wheel wear condition and the stationary and running of vehicle.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.443-448
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• 2020

In this study, field measurements were performed to analyze the effects of train types (AREX, AREX Express, KTX, KTX-Sancheon) and train speeds on the dynamic behavior of the direct fixation track structure on Yeongjong grand bridge by bridge type (truss bridge, suspension bridge). Based on field measurement results, the track impact factor and train running stability (coefficient of derailment, Rate of wheel load reduction, lateral displacement of rail head) are compared with domestic and foreign standards and regulations to influence the dynamic behavior of direct fixation track. As a result, the differences in the dynamic behavior of the direct fixation tracks by the type of bridges of Yeongjong bridge are not significant, but it was analyzed that these were more directly affected by the magnitude of the train load. Therefore, it is necessary to establish the reinforcement plan of the direct fixation track structure on Yeongjong grand bridge in consideration of the increase of the track impact factor and dynamic track force.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.2
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• pp.69-73
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• 1998

With increased loads in steered wheels and wider section tires the effort required at the steering wheel makes the driver's job very tiring and difficult. Improvements such as an increase in the mechanical efficiency of the steering system or lower steering box ratios help the reduce driver fatigue. Now using of power steering is increasing. It needs to be considering parts size of steering system as using power steering. This paper presents adjust part size of steering system form estimating reliability according to reducing torque under the dynamic load, In this paper, the spider of universial joint is selected to prove relation between steering and power steering reliability.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.12
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• pp.1296-1303
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• 2012

There is a certain limit to reproduce phenomena between the real vehicle and road, since the existing methods to verify durability of the wheel are mostly uni-axial tests. And the change of durability of the wheel can't be predicted since these tests don't consider the camber angle and lateral force as important factors. In this paper, the FE models of the wheel-tire and drum are created. Then, the vertical and lateral loads are applied to wheel-tire assembly and the camber angle is applied by inclining the wheel-tire assembly to the drum. Based on the analysis result, the crack position is predicted to be created in the body of the wheel. The variation of the stress according to the camber angle is verified and the maximum spot of the stress changes continually.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.109-116
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• 2000

The objective of this study is to measure rim surface adhesion and to calculate motion resistance produced by the adhesion acting on the rim section of a circular wheel under sticky soil condition. The mechanisms of generating motion resistance by the adhesion on a circular wheel were analyzed through wheel motion. Experiments were conducted in an indoor soil bin that contains loam soil. A circular steel wheel was used for experiments. A part of the wheel rim was cut off, and transducers which can measure normal and tangential forces were installed in this section. Calculated motion resistance at a part of the rim section was superposed for one wheel rotation as motion resistance produced by the rim surface adhesion. The motion resistance increased with increasing the dynamic load. Ratio of the motion resistance to total motion resistance measured by an axis transducer was about 23 to 46 % in this study.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.1094-1099
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• 2002

In this paper, a numerical method for vehicle-track interaction analysis is developed to evaluate vertical dynamic force subjected to rail surface. A vehicle is modelled by lumped masses system and track by multi layered continuous beam system. The equation of motion of vehicle and track interaction system is derived by considering compatibility condition at the contact points between wheel and rail. The input vibration source is given by the empirical formula of power spectral density of track irregularity, which is suggested by FRA. Using this method, dynamic impact factors with the train speed are evaluated.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.337-342
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• 2003

The dynamic load effects are conveyed to the railway bridges through tracks which are generated by moving trains The dynamic load effects may vary due to the dynamic characteristics of the applied vehicle loads and the railway bridges containing the track system. However, the track effects have been neglected or simplified by spring elements in the most studies since it is quite complex to consider the track systems in the dynamic analysis models of railway bridges. In this study, track system on railway bridges is modeled using a three-dimensional discrete-support model that can simulate the load carrying behavior of tracks. In addition, this program is developed with the precise 20-car model and a continuous PSC(prestressed concrete) box girder bridge, which is the main bridge type of Korea Train express(KTX). Three-dimensional elements are used for both. The dynamic response of railway bridges is found to be affected depending on whether the track model is considered or not. The influencing rate depends on the traveling speed and different wheel-axle distance. The dynamic bridge response is decreased remarkably by the track systems around the resonant frequency. Therefore, the resonance effect can be reduced by modifying the track properties in the railway bridge.